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000
FXUS63 KBIS 030329
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
929 PM CST MON DEC 2 2013

.UPDATE...
ISSUED AT 925 PM CST MON DEC 2 2013

THE NEXT SURGE OF SNOW NOW IDENTIFIED ON RADAR MOVING INTO EASTERN
MONTANA AND SOUTHWEST NORTH DAKOTA. VISIBILITIES AROUND ONE HALF
MILE TO 2 MILES REPORTED FROM MILES CITY TO WOLF POINT. COOLING IR
CLOUD TOPS CORRESPOND WELL TO H300 WARM ADVECTION FIELD AHEAD OF
THE UPPER LOW IN MONTANA THAT WILL MOVE INTO NORTH DAKOTA. EXPECT
TO SEE SNOW OVERSPREAD THE REGION AGAIN LATER TONIGHT THROUGH
TUESDAY. WINTER STORM WARNING SET TO BEGIN ACROSS THE SOUTH
CENTRAL AT MIDNIGHT TONIGHT. TIMING MAY BE A LITTLE FAST...BUT
TRENDS LOOK VERY GOOD.

UPDATE ISSUED AT 645 PM CST MON DEC 2 2013

SEVERAL UPPER LOW CENTERS OVER MONTANA WILL DUMBELL AROUND EACH
OTHER OVER THE NEXT 24 HOURS. ONE PORTION OF THIS TWO HEADED
STORM WILL MOVE THROUGH SOUTHERN NORTH DAKOTA ON TONIGHT AND
TUESDAY...BRINGING A BAND OF HEAVY PRECIPITATION ACROSS THE NORTH
AND SOUTH DAKOTA BORDERS. CURRENTLY VISIBILITIES IN THE SNOW AREA
ACROSS NORTHERN NORTH DAKOTA RANGE FROM 1 TO 3 MILES. ITS
POSSIBLE THE THE SNOW ACROSS THE NORTH HALF OF THE REGION MAY
EVEN DIMINISH A LITTLE TONIGHT. HOWEVER AS THE SURFACE WINDS PICK
UP ON TUESDAY THE SNOW AND BLOWING SNOW WILL CAUSE REDUCED
VISIBILITIES AND DRIFTING. THE NEW ACTION WILL BE SNOW ACROSS THE
SOUTH LATER TONIGHT. THIS IS SHOWING UP ON BILLINGS RADAR NOW AND
SEEING THIS INCREASING PRECIPITATION ALSO ON RAPID CITY AND
BOWMANS RADAR. THIS AREA OF PRECIP WILL MOVE INTO SOUTHERN NORTH
DAKOTA TONIGHT...THUS WILL SEE RAPIDLY DETERIORATING CONDITIONS
AFTER MIDNIGHT. CURRENT FORECAST STILL LOOKS OK.

&&

.SHORT TERM...(THIS AFTERNOON THROUGH WEDNESDAY)
ISSUED AT 325 PM CST MON DEC 2 2013

THE MAIN FORECAST CONCERN WILL BE THE WINTER STORM CURRENTLY
AFFECTING NORTHERN NORTH DAKOTA. THE WINTER STORM IS EXPECTED TO
WRAP-AROUND AND DEVELOP ACROSS SOUTHWESTERN NORTH DAKOTA THIS
EVENING...THEN MOVE EAST INTO SOUTH CENTRAL AND SOUTHEASTERN NORTH
DAKOTA AFTER MIDNIGHT TONIGHT.

THE MEDIUM RANGE MODELS STILL DIFFER WITH RESPECT TO HOW AN UPPER
LEVEL LOW CRASHING ASHORE THE PACIFIC NORTHWEST WILL EVOLVE OVER THE
NORTHERN PLAINS THROUGH WEDNESDAY. THE LATEST ECMWF/GEM CONTINUE TO
MORPH THE FEATURE INTO A POSITIVELY TILTED OPEN WAVE OVER THE
NORTHERN ROCKIES TUESDAY...THEN PUSH IT INTO THE NORTHERN PLAINS
WEDNESDAY. WEAK WAVES AHEAD OF THE FEATURE WILL GENERATE SNOW OVER
NORTH DAKOTA. HOWEVER...THE LATEST NAM (AND GFS TO A LESSER EXTENT)
PROG A STRONGER SHORTWAVE TO EJECT AHEAD OF THE PARENT LOW ACROSS
SOUTHERN NORTH DAKOTA TUESDAY. THIS SOLUTION WOULD GENERATE HEAVY
SNOWFALL ACROSS THE ND/SD BORDER TUESDAY.

GIVEN THE MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...WILL TAKE
A BLENDED APPROACH FOR THIS FORECAST. THE COMBINATION OF THE ONGOING
SNOW NORTH (AND HIGHER SNOW TO LIQUID RATIOS)...SNOW DEVELOPMENT
SOUTH WITH HIGH PRECIPITATION RATES TONIGHT...AND SNOW AREA WIDE
TUESDAY SHOULD GENERATE WIDESPREAD SNOW TOTALS OF 6 TO 8 INCHES BY
WEDNESDAY. TOTALS OF 8 TO 10 INCHES WILL BE POSSIBLE ACROSS THE
JAMES RIVER BASIN WHEN ALL IS SAID AND DONE. THE WINTER STORM
WARNING HEADLINES HAVE ALREADY BEEN SENT.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 325 PM CST MON DEC 2 2013

FORECAST HIGHLIGHTS IN THE LONG TERM PERIOD WILL BE LINGERING
CHANCES FOR ACCUMULATING SNOW AND LIKELY BLOWING SNOW ON WEDNESDAY
NIGHT...AND VERY COLD AIR SURGING INTO THE REGION THROUGH THE
PERIOD.

WEDNESDAY NIGHT THE LARGE UPPER LEVEL LOW/TROUGH OVER SASKATCHEWAN
EXTENDS SOUTHWARD ACROSS THE SOUTHERN ROCKIES. THIS LARGE TROUGH IS
FORECAST TO REMAIN OVER THE REGION...PERHAPS ONLY A SLIGHT REPRIEVE
NEXT MONDAY (THE END OF THE LONG TERM FORECAST PERIOD)...BEFORE THE
NEXT REINFORCEMENT OF ARCTIC AIR PLUNGES SOUTHWARD FROM NORTHERN
CANADA.

SPECIFICS FOR WEDNESDAY NIGHT INCLUDE THE SNOW FINALLY ENDING FROM
WEST TO EAST ACROSS WESTERN AND CENTRAL NORTH DAKOTA WITH ONLY LIGHT
SNOW ACCUMULATIONS. HOWEVER...NORTHWEST WINDS OF 15 TO 20 MPH WILL
KEEP AREAS OF BLOWING SNOW LINGERING WEDNESDAY NIGHT.

THE BIG STORY AFTER THE SNOWFALL THROUGH WEDNESDAY AFTERNOON WILL BE
THE FRIGID ARCTIC AIR THAT WILL SURGE INTO NORTH DAKOTA. LOW
TEMPERATURES FROM WEDNESDAY NIGHT THROUGH NEXT MONDAY NIGHT ARE
FORECAST TO BE BELOW ZERO. HIGH TEMPERATURES WILL STRUGGLE TO CLIMB
ABOVE ZERO...OR REMAIN BELOW ZERO.

WEDNESDAY NIGHT/THURSDAY MORNING LOWS SHOULD RANGE FROM 5 TO 15
BELOW ZERO...WITH WIND CHILLS OF 25 TO 35 BELOW ZERO. A WIND CHILL
ADVISORY WILL LIKELY BE NEEDED FOR THIS TIME PERIOD.

THURSDAY HIGH TEMPERATURES SHOULD RANGE FROM ZERO TO 10 BELOW WITH
WIND CHILLS THURSDAY AFTERNOON IN THE 15 TO 30 BELOW ZERO RANGE.

THE COLDEST AIR WILL ARRIVE THURSDAY NIGHT AND CONTINUE THROUGH THE
WEEKEND. LOWS THURSDAY NIGHT...FRIDAY NIGHT...AND SATURDAY NIGHT ARE
EXPECTED TO RANGE FROM 10 TO 20 BELOW ZERO. WIND CHILLS AT NIGHT
SHOULD PLUNGE TO 30 TO NEAR 45 BELOW ZERO. IN ADDITION...HIGH
TEMPERATURES FRIDAY AND SATURDAY WILL LIKELY NOT REACH ZERO. LOOKING
AT HIGHS FROM NEAR ZERO TO 10 BELOW FOR THESE 2 DAYS. WIND CHILL
WARNINGS AND ADVISORIES WILL LIKELY BE NEEDED FROM THURSDAY NIGHT
THROUGH THE WEEKEND.

ONLY A WEAK RECOVERY IN TEMPERATURES SUNDAY AND MONDAY WITH HIGHS OF
5 BELOW TO 5 ABOVE ZERO. BEYOND THE OFFICIAL LONG TERM FORECAST
PERIOD THE MODELS ARE DEPICTING YET ANOTHER ARCTIC AIRMASS TO SURGE
SOUTH ACROSS THE NORTHERN PLAINS BEGINNING NEXT TUESDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 925 PM CST MON DEC 2 2013

HAZARD TO AVIATION WILL FOCUS ON WINTER STORM SPREADING ANOTHER
ROUND OF SNOW INTO NORTH DAKOTA TONIGHT. GENERALLY MVFR CONDITIONS
FROM KISN-KMOT-KBIS-KJMS WILL DETERIORATE TO IFR IN SNOW AND LOW
CLOUDS THROUGH TONIGHT. AFTER 12Z TUESDAY IN ADDITION TO THE IFR
CONDITIONS...INCREASING NORTHWEST WINDS WILL REDUCE VSBY. EXPECT
IFR TO LOW IFR CONDITIONS ACROSS WEST AND CENTRAL NORTH DAKOTA
AFTER 12Z.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 6 PM CST /5 PM MST/ WEDNESDAY FOR
NDZ019-020-034>036-042-045>048-050-051.

WINTER STORM WARNING UNTIL 6 PM CST /5 PM MST/ WEDNESDAY FOR
NDZ001>005-009>013-017-018-021>023-025-031>033-037-040-041-043-
044.

&&

$$

UPDATE...WAA
SHORT TERM...TM
LONG TERM...JV
AVIATION...WAA